Cr(VI)-induced DNA damage is lessened by the modulation of hsp70 via increased GSH de novo synthesis in Drosophila melanogaster.

Hexavalent chromium [Cr(VI)] is a genotoxic chemical, and in the chemical-exposed organism, oxidative stress is one of the leading causative mechanisms of genotoxicity. Heat shock protein-70 (Hsp70) is reported to be modulated in environmental chemical exposed organisms. Inadequate information on the protective role of Hsp70 in chemical-induced DNA lesions prompted us to investigate this possibility in a well-studied genetically tractable in vivo model Drosophila melanogaster. In the midgut cells of Cr(VI)-exposed hsp70-knockout (KO), -knockdown (KD), and -overexpression Drosophila strains, no significant change in double-strand breaks generation was observed in comparison to similarly exposed w 1118 and the respective genetic control strain after 48 h. Therefore, the role of hsp70 was investigated on oxidative DNA damage induction in the exposed organisms after 24 h. Oxidized DNA lesions (particularly oxidized purine-based lesions), 8-oxo-dG level, and oxidative stress endpoints were found to be significantly elevated in hsp70-KO and -KD strains in comparison to similarly exposed w 1118 and respective genetic control strain. On the contrary, in ubiquitous hsp70-overexpression strain exposed to Cr(VI), these endpoints were significantly lowered concurrently with increased GSH level through elevated gclc, and gclm expression, Gclc level, and GCL activity. The study suggests that as a consequence of hsp70 overexpression, the augmented GSH level in cells vis-a-vis GSH de novo synthesis can counteract Cr(VI)-induced oxidized DNA lesions.

Mutation in Drosophila methuselah resists paraquat induced Parkinson-like phenotypes.

Parkinson's disease (PD) is a prevalent and devastating neurodegenerative disorder having limited cure options and strong association with the loss of dopaminergic neurons in the substantia nigra region of the mid brain. Etiology of PD includes both genetic and environmental factors. Paraquat (PQ), a widely used herbicide, is known to be associated with pathogenesis of PD. We report that a mutation in Drosophila methuselah (mth(1)), which is associated with aging, has a role in preventing dopaminergic neuronal cell death in PQ-exposed organism. Exposed mth(1) flies exhibit significant resistance against PQ-induced Parkinson's phenotypes and behavior in terms of oxidative stress, dopaminergic neuronal degeneration, locomotor performance, dopamine content, phosphorylated JNK, pFOXO, Hid, and cleaved caspase-3 levels. Conversely, over-expression of mth in dopaminergic neurons makes the exposed organism more vulnerable to oxidative stress, neuronal cell death, and behavioral deficit. The study suggests that lesser activation of JNK-mediated apoptosis in dopaminergic neurons of exposed mth(1) flies protects the organism from PQ-induced damage, which may be causally linked to a common mechanism for PQ-induced neurodegeneration.